For the floating offshore wind turbine (FOWT), except for wind and wave effect, the current effect have an important impact on the dynamic responses of the wind turbine system. In this paper, a 6MW spar type FOWT system are investigated both experimentally and numerically to study the current effect on the hydrodynamic responses of spar type FOWT. The vortex induced motions (VIMs) phenomenon is clearly observed in the model test result. The results of model test and numerical simulation are compared and analyzed to study the VIM characteristics of the FOWT system. Furthermore, the wave-current coupling effect on VIM of the FOWT system is also investigated and obtained.
In recent years, wind power has become the fastest growing renewable energy source in many parts of the world and the research focus has shifted from onshore to offshore wind energy. Due to the water depth and power restriction of the land-based wind turbine, the floating offshore wind turbine (FOWT) have become the focus of research (Meng L. et al 2018). As a collection device of offshore wind energy, the environmental load of FOWT mainly includes wind, wave and current load. Some researchers have conducted a series of experiments on FOWTs for dynamic response analysis (Zhao Y S. et al 2016a; Meng L. et al 2019). In addition, numerical simulation tools have been applied to conduct analyses in OC3 to OC5 projects (Offshore Code Comparison Collaboration Continued, with Correlation), and many numerical simulation codes have been developed and improved for the fully coupled analysis of FOWTs (Jonkman J. et al 2010; Karimirad M. et al, 2012; Coulling A. et al. 2013). However, very few studies have been performed to investigate the current effect on the hydrodynamic response of spar type FOWTs. The spar type FOWTs, as a cylindertype floater, exposed to a current load may experience alternate vortex shedding on both sides of the floater, resulting in periodic vortex induced motions (VIMs), which may lead to the rapid accumulation of structural fatigue damage to the mooring positioning system. Thus, the correct calculation of current load is of great significance to the safety of FOWT and the design of the mooring positioning system.